JP2003202106A - Re-combustion furnace for waste thermal decomposition gas and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water jetting gas cooling re-combustion furnace capable of preventing the development of NOx and the melting and adhesion of dust, as well as of reducing the amount of dioxin in exhaust gas and preventing an increase in the amount of the exhaust gas, by mixing sprayed water in combustion gas extremely uniformly for properly lowering combustion gas temperature. <P>SOLUTION: An inlet port 13 for thermal decomposition gas G is provided on the top of the re-combustion furnace 11. A plurality of combustion air blowing openings 15a are provided around the inlet port 13 in the peripheral direction to constitute a re-combustion burner 12. A ring-shaped cooling water header 16 for spraying cooling water into the furnace 11 together with air from the respective air blowing openings 15a is provided at the re-combustion burner 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to general waste (household waste), industrial waste (factory waste), flammable waste such as waste oil and waste liquid, blown with oxygen and the like in a gasification melting furnace. Hydrocarbons, organic substances generated in the furnace when burning,
It relates to a re-combustion furnace for waste pyrolysis gas for complete combustion of flammable pyrolysis gas containing oil vapor and corrosive gas such as dust and hydrogen chloride together with the dust. The present invention relates to a re-combustion furnace of a system in which heat retained by pyrolysis gas generated in a blast furnace or the like is recovered by a boiler and a control method thereof.

[0002]

2. Prior Art and Problems to be Solved by the Invention
Basic matters: When waste is incinerated or heated indirectly, as in a direct smelting furnace (gasification and melting furnace that directly gasifies waste and melts dust), gas is generated from the waste. This gas is called pyrolysis gas and is flammable. Generally, a furnace that mixes air with such pyrolysis gas and burns it is called a re-combustion furnace, and a furnace of a system in which water is sprayed to the high-temperature combustion gas generated in the re-combustion furnace to cool it is the object of the present invention. However, the basic functions that such a reburning furnace should have are as follows. That is, the function: dust does not adhere to or grow on the inner wall of the reburn furnace.

Function: The residence time of gas at 850 ° C. or higher in the reburning furnace is 2 seconds or longer.

Function: The solid combustible substances (for example, char) contained in the pyrolysis gas are completely burned out (the combustible substances are hardly contained in the finally separated dust).

Function: C contained in reburning furnace outlet gas
The amount of O and NOx is as small as possible.

Function: The total cost of equipment including other equipment is not excessive.

Function: Even if the quality of waste, for example, the latent heat of combustion of waste (low heating value, LHV) changes greatly,
Being able to always exhibit the basic functions from above.

However, the conventional reburning furnace cannot satisfy all the above basic functions. Hereinafter, typical conventional techniques will be described, and the reasons why the above functions are not satisfied by those techniques will be specifically described.

2. Prior art (prior art) 1) Prior art-A (simple refractory-clad inner wall structure type re-combustion furnace: refer to FIG. 7) In this technology, air is mixed with pyrolysis gas for combustion, and the generated combustion gas is re-combusted. After exiting the furnace 51, water is sprayed and cooled in a gas cooling chamber (not shown). In the present technology, since the pyrolysis gas has a large calorific value, if it is simply burned, the temperature becomes extremely high (for example, the adiabatic theoretical temperature of 2000 ° C.), and the following problems occur. Note that this type of technique is described in, for example, Japanese Patent Laid-Open No. 8-121728.

(1) A large amount of thermal NOx (When burned at a high temperature, a large amount of harmful NOx is generated.
x is called thermal knox). That is,
The above basic functions are not satisfied.

(2) The dust contained in the gas melts and collides with the inner wall of the entire recombustion furnace and the inner wall of the outlet to adhere and grow, eventually obstructing the gas flow and making continuous plant operation impossible. To That is, the above basic functions are not satisfied.

2) Prior art-B (water-injection type refractory-clad inner wall structure type re-combustion furnace: see FIG. 10) In the present technology, the cooling water is directly sprayed into the combustion gas to control the gas temperature of the re-combustion furnace 61. Since the temperature can be controlled to an appropriate low temperature (an appropriate temperature at which thermal knox does not occur and the problem of dust melting and adhesion does not occur, for example, 900 ° C.), there is no defect such as A above. Even if the LHV of the waste fluctuates, the combustion chamber 61 can be changed by changing the amount of cooling water sprayed.
The internal gas temperature can be maintained appropriately. However, this technique has a serious problem. That is, since the amount of heat generated by the pyrolysis gas is excessive, a large amount of water must be sprayed. For example, with a calorific value of 2000 kcal / Nm ³ , 20
In order to burn the pyrolysis gas of 00 Nm ³ / h and cool it to 900 ° C., about 3000 kg / h of water must be sprayed. When such a large amount of water is blown into the furnace, it is impossible to uniformly mix the spray water with the combustion gas, which causes the following problems. A technique of this kind is described in, for example, Japanese Patent Laid-Open No. 11-182827.

(1) The pyrolysis gas is cooled after burning. That is, since the combustion is performed at a high temperature, there are two problems as in the case of the conventional technique-A described above. Of course, since the combustion is not carried out instantaneously but in a flame, the problem of the present technology is somewhat less than that of the conventional technology-A.
The problem still remains.

(2) Since it is impossible to completely mix a large amount of water with the combustion gas, the combustion gas and the spray water become non-uniform. That is, there are a part that is partially overcooled and a part that is insufficiently cooled, and finally, the temperature is about 900 ° C., which is the required temperature when they are further mixed. As a result, the following problems occur.

In order to quickly mix a large amount of water with the combustion gas, a large amount of water must be sprayed during the flame. The flame contains combustible gas and combustible dust that have not been completely burned, and they are supercooled by a large amount of water, so that a part of the flammable gas flows downstream without being combusted. Further, since the gas is also supercooled, it does not burn out sufficiently, and for example, a large amount of CO gas, which is a problem in terms of atmospheric pollution, remains. Further, since flammable dust remains and is overcooled, harmful dioxins are not synthesized or decomposed.

(3) The recombustion furnace originally properly burns the pyrolysis gas to completely burn unburned dust in the burned gas, and at the specified temperature for decomposing dioxin contained in the combustion gas, For example, it has a role of staying at 900 ° C. for 2 seconds. However, in the present technology, since the non-uniform cooling is performed, it is necessary to secure the combustion gas residence time in the furnace longer than 2 seconds. This means that a large-sized reburning furnace is required, which causes an increase in equipment cost.

3) Prior art-C (circulating exhaust gas blowing type reburning furnace: see FIG. 11) As described above, the gas leaving the reburning furnace is cooled and dust-removed, and then released to the atmosphere as exhaust gas. Such cooling
The conventional technique is to blow the exhaust gas after dust removal into the reburning furnace 71. That is, in the present technology, the circulating exhaust gas having a low temperature can be blown into and mixed with the combustion gas to control the gas temperature of the re-combustion furnace 71 to an appropriate low temperature.
There is no such drawback. Further, even if the LHV of the waste fluctuates, the gas temperature in the reburning furnace can be properly maintained by changing the amount of exhaust gas to be blown. However, since the combustion in the burner is carried out at a high temperature, the gas temperature immediately after the combustion becomes high, and there are two problems as in the case of the conventional technique-A described above. Of course, in the present technology, since it is cooled by the circulating exhaust gas after combustion, even if the dust is melted, it is cooled, and as a result, the adhesion to the inner wall is reduced. It is alleviated, but the problem still remains.

Further, a drawback of the present technique is that the flow rate of exhaust gas is increased and the basic function described above is not satisfied by blowing gas. That is, since the flow rate of the entire combustion gas increases (for example, the gas amount increases by 40%), the boiler, the dust collector (bag filter), the poisonous gas treatment device in the gas, and the gas-induced draft fan located in the downstream side There is a drawback that equipment costs increase. Although there is a conventional technique of reducing NOx by mixing exhaust gas into the burner body to lower the combustion gas temperature, the drawback of increasing the exhaust gas flow rate still remains. This type of technology is disclosed in, for example, Japanese Patent Laid-Open No. 7-29
It is described in Japanese Patent No. 3844. 4) Conventional Technology-D (Swirl Melting Furnace: See FIG. 12) In the present technology, a large amount of air is blown into the re-combustion furnace 81 to completely burn at once, and the combustion gas temperature is set to a high temperature (for example, 160).
This is a method in which the dust contained in the gas and ash generated in other places are melted at 0 ° C.) and taken out as slag from the bottom. With this method, a large amount of thermal NOx is generated,
Moreover, the refractory of the wall is worn by the molten slag, or it is necessary to use a very expensive high-grade refractory material as the refractory for the wall. Furthermore, when the amount of waste to be processed is small or the LHV of the waste (this LHV fluctuates quite normally) is small, the amount of heat entering the reburning furnace 81 is insufficient (the combustion gas temperature melts dust. Since the amount of heat is insufficient to raise the temperature above the temperature, extra fuel (L
It has the drawback that it must be blown with PG and heavy oil. Furthermore, it is necessary to operate properly so that the slag does not adhere to the inner wall surface of the reburning furnace or the slag discharge port, which makes the operation very complicated. As a result of the above, the conventional technique does not satisfy the basic functions and features that the above-described reburning furnace should have.

The present invention has been made in order to solve the problems of the above-mentioned respective prior arts, and an object of the present invention is to prevent sprayed water in a re-combustion furnace of a water injection type gas cooling system. The temperature of the combustion gas is accurately lowered by mixing it in the combustion gas extremely uniformly, generating NOx and melting dust.
It is an object of the present invention to provide a furnace structure and a control method thereof that can prevent not only adhesion but also reduction of the amount of dioxin in exhaust gas and prevention of increase of exhaust gas amount.

[0020]

In order to achieve the above object, the recombustion furnace for waste pyrolysis gas according to claim 1 of the present invention comprises: a) general waste, industrial waste, waste oil, waste liquid, etc. Hydrocarbons, organic substances, oil vapors that are generated by the thermal decomposition of the above-mentioned combustible waste by either partially burning or indirectly heating the combustible waste And a re-combustion furnace of waste pyrolysis gas for completely combusting a combustible pyrolysis gas containing a dust and a corrosive gas such as hydrogen chloride together with the dust, and b) at an end of the re-combustion furnace. A recombustion region (hereinafter also referred to as a recombustion burner) is provided by providing a plurality of combustion air blowing ports around the introduction port of the pyrolysis gas, and c) the recombustion burner. Blow each of the above air The cooling water from seeing the mouth is characterized in that a water spray device for spraying the furnace together with the air.

In the waste pyrolysis gas re-combustion furnace having the above-mentioned structure, the combustion air is blown into the pyrolysis gas flowing from the inlet of the furnace top from the surroundings, so that the pyrolysis gas is aired. Are mixed and the pyrolysis gas is reburned. At this time, when a large amount of air is mixed, the temperature of the reburning gas rises at once, and when the temperature rises to, for example, 1600 ° C. or higher, thermal NOx is generated and dust contained in the pyrolysis gas is melted to melt the furnace wall. However, since the cooling water is atomized and mixed with the pyrolysis gas along with the air, the temperature of the reburning gas decreases and NOx generation and melting / adhesion of dust are suppressed. To be Further, since the cooling water is atomized together with the air and is blown into the reburned gas, the temperature is lowered as a result of uniform mixing. That is, the re-combustion furnace of the present invention not only sprays and cools the combustion gas with water, but also sprays and cools water inside the re-combustion burner, so that the sprayed water is extremely uniformly dispersed in the combustion gas. As a result of being mixed, the combustion gas temperature is lowered to prevent generation of NOx and melting / adhesion of dust, and it has advantages such as reduction of the amount of dioxins in exhaust gas and prevention of increase of exhaust gas amount.

As described in claim 2, each of the air blowing ports is inclined or twisted so that a swirl flow is generated around the gas flow introduced from the introduction port of the pyrolysis gas, and each air blowing port is blown. It is desirable to provide a cylindrical air header so as to surround the mouth, and to provide a cooling water header in which a plurality of cooling water spray nozzles are provided in the circumferential direction so as to face the air blowing openings.

According to the second aspect of the present invention, in the reburning furnace, the cooling water injected from the cooling water header in the air header is atomized and uniformly mixed with the air, and the cooling water is cooled together with the air from the plurality of air blowing ports. Water is blown into the furnace. At this time, since the air and the cooling water generate a swirling flow around the pyrolysis gas flowing into the furnace, the air and the cooling water are sufficiently and uniformly mixed in the pyrolysis gas, and the temperature of the reburned gas is increased. Is uniformly reduced.

According to the third aspect of the present invention, a cooling water spray pipe may be provided at the central axis portion of the introduction port for the pyrolysis gas so that the nozzle at the lower end of the cooling water spray pipe faces the central portion of the furnace.

According to the third aspect of the present invention, in the case where the temperature of the reburning gas cannot be sufficiently lowered only by blowing the atomized cooling water together with the air from the periphery of the pyrolysis gas as described above. In addition, the temperature of the reburning gas can be lowered to a predetermined temperature by spraying cooling water into the central portion of the pyrolysis gas and blowing the cooling water.

According to a fourth aspect of the present invention, a plurality of cooling water spray pipes are circumferentially spaced above the reburning furnace, and the length of the flame generated during reburning of the injection nozzle at the tip (upstream. The distance can be set so as to be inclined toward the central axial line in the furnace toward the downstream side so that the cooling water is blown toward the front end direction more than ½ of the distance (in the downstream direction).

Actually, not all of the pyrolysis gas is burned instantaneously immediately after the pyrolysis gas introduction port of the reburning burner, but it is burned uniformly in the entire flame part, so the point of injection of water into the flame is the flame. If it is not blown in the tip direction from at least ½ of the length, there is a risk of leaving an unburned portion. However, according to the reburning furnace of claim 4, water is sprayed without leaving an unburned portion. The temperature of the combustion gas can be lowered.

According to a fifth aspect of the present invention, the furnace shape in the downstream direction of the re-combustion region of the re-combustion furnace top is provided with an upper end of a truncated cone shape or a cylindrical shape (flame-holding cylinder shape) whose diameter gradually decreases toward the upstream side. It is preferable that the shape of a truncated cone whose diameter is gradually reduced in the upstream direction is integrated.

According to the reburning furnace of claim 5, the flame at the time of the recombustion of the pyrolysis gas of the reburning burner is surrounded by the surrounding furnace wall, and the spread of the flame is prevented, so that the flame is stable, Combustion becomes good.

According to a sixth aspect of the present invention, an air blowing tube can be provided at the center of the introduction port for the pyrolysis gas at the top of the re-combustion furnace with the blowing port at the lower end facing the inside of the furnace.

There is a case where the temperature of the combustion gas cannot be appropriately lowered only by injecting the cooling water, and in that case, it is necessary to blow a little air. However, when a large amount of air is blown from around the pyrolysis gas, the mixture of the pyrolysis gas and air deteriorates, good combustion cannot be obtained, and there is a risk that the air will blow out. For example, since an air blowing tube is also provided in the center of the reburning burner section, a large amount of air from inside and outside of the air blown from the blow opening at the lower end and the air blown from the air blowing nozzles around it are decomposed. It mixes well with gas.

As described in claim 7, the cooling water supply pipe and the fuel supply pipe can be connected to the cooling water spray pipe through the switching valve.

According to the recombustion furnace of claim 7, the pyrolysis gas is mixed with the air blown from the surroundings from the nozzle at the lower end of the cooling water injection pipe in the pyrolysis gas injection center in the recombustion burner. Immediately before being combusted and burned, cooling water is blown into the pyrolysis gas. Of course, as in the reburning furnace of claim 2, air is blown into the furnace from a plurality of air blowing nozzles of the air header, and is mixed well with the pyrolysis gas and burned. Moreover, by switching the switching valve of the cooling water injection pipe, preheating can be performed by blowing auxiliary fuel such as LPG or heavy oil from the fuel supply pipe during warming up preheating of the reburning furnace at startup.

As described in claim 8, the cooling water spray pipe or the air blowing pipe may be made of a metal pipe, and the outer wall surface of the pipe may be coated with a refractory refractory material (castable refractory material or porcelain ceramics). it can.

According to the eighth aspect of the present invention, when the temperature of the pyrolysis gas is high, hydrogen chloride gas contained in the pyrolysis gas may corrode the metal portion of the cooling water spray pipe or the air blowing pipe. However, since it is covered with refractory refractory (castable refractory or porcelain ceramics), there is no such possibility.

As described in claim 9, as a part of the cooling water, sewage produced in the dust pit or compressed by a duster and separated from dust can be used.

According to the re-combustion furnace of the ninth aspect, combustion treatment can be performed by blowing sewage or the like, which is difficult to treat, into the combustion gas.

A control method for a reburning furnace according to claim 10 is:
Adiabatic theoretical combustion flame temperature in the re-combustion furnace is 1400-1
The temperature is controlled to be 600 ° C., and then is lowered to near 900 ° C. (850 ° C. or higher) by spraying cooling water on the flame, and the temperature of the combustion gas is locally at least 500
The feature is that the temperature is controlled to be ℃ or higher.

According to the method for controlling a re-combustion furnace of the tenth aspect, the adiabatic theoretical combustion flame temperature is 1400 by spraying water from around the combustion gas inlet in the re-combustion burner section.
Controlled to ~ 1600 ° C to prevent a large amount of thermal NOx and dust from melting instantaneously and adhering to the furnace wall surface, and then dioxins can be decomposed by the cooling water blown to the tip of the flame. It is lowered to 900 ° C. All of the pyrolysis gas does not burn instantaneously immediately after the inlet of the reburning burner, but burns uniformly over the entire flame section, so the temperature of the combustion gas cooled by spraying with water is ideal. Should be uniform, but in practice it will be uneven. However, even if it becomes non-uniform, if the temperature is not at least 500 ° C. or more, CO of unburned gas remains, so gas cooling by water injection is controlled so that such unburned gas CO does not remain. There is.

According to the eleventh aspect of the present invention, the control of the reburning burner is performed while keeping the amount of blown air constant.
The temperature inside the furnace can be kept constant by controlling only the amount of cooling blown water.

According to the control method of the re-combustion furnace of the eleventh aspect, the control of the re-combustion burner (re-combustion region) is performed only by controlling the injection amount of the cooling water. That is, the amount and composition of the pyrolysis gas introduced into the reburning furnace fluctuates, but in order to respond to the fluctuation, it is necessary to control only the amount of water blown so that the temperature inside the furnace is usually constant around 900 ° C. Good. On the other hand, the blown air amount is not included in this adjustment loop, and a constant flow rate (slightly increased) is secured.

[0042]

FIG. 8 is a schematic diagram showing an example of an exhaust gas treatment facility including a waste gasification and melting furnace and a reburning furnace.

As shown in FIG. 8, the gasification and melting furnace 1 for waste incineration is composed of a vertical shaft furnace, and the combustion gas in which the molten slag take-out port 2a is opened to one side at the lower end opening of the furnace. The blow-in furnaces 2 are integrally connected to each other, and a plurality of combustion burners 2b for blowing the oxygen-containing fuel gas into the combustion-gas blow-in furnaces 2 are arranged inward. An input port 1c for the waste A is provided in the upper portion of the furnace 1, and the waste A compressed by the duster 5 and dehydrated is input. It is thrown into the throwing hopper 5a by the crane 3a from the waste pit 3. The waste A is crushed by the crusher 4 before being charged and is charged into the charging hopper 5a, and then the iron material and the like in the waste A is suctioned and removed by the magnetic separator 7, and then it is charged into the dust collector 5. The dust collector 5
Sewage produced when the waste A is compressed and dehydrated therein is sprayed into the re-combustion furnace 11 described later and treated.

The waste A introduced into the furnace 1 is successively dried and pyrolyzed, and then burned and melted to dissolve the incombustibles in the waste A into molten slag droplets, and the discharge port 2
It is discharged from a. The molten slag droplets are put into the water granulation tank 6, cooled and solidified, and taken out as slag. The pyrolysis gas G generated in the furnace 1 is discharged to the exhaust gas treatment facility 10 through an exhaust port 1d provided at the top of the furnace. The exhaust gas treatment facility 10 is provided with a re-combustion furnace 11 of a water injection type gas cooling system which is a characteristic part of the present invention, and a gas introduction of a re-combustion burner (re-combustion region) 12 part provided at the top of the re-combustion furnace 11. The port 13 is connected from the exhaust port 1d of the gasification and melting furnace 1 through the exhaust duct 9. Reference numeral D in FIG. 8 indicates a dome-shaped melting zone (melting dome) formed in the lower truncated cone of the gasification melting furnace 1. The exhaust gas treatment facility 10 is
As shown in FIG. 8, on the downstream (wake) side of the reburning furnace 11,
A dehumidifier 41, a dust collector (bag filter) 42, an induction blower (IDF) 44, and a chimney 45 are provided in this order by being connected in series, and a slaked lime charging portion 43 is provided near the entrance of the dust collector 42.
Is provided. The waste incineration treatment facility of this example is a small-scale facility with a waste treatment amount of 100 tons / day or less and does not recover heat by the boiler. On the other hand, although illustration is omitted, in the case of a large-scale facility with a waste treatment amount of 100 tons / day or more, it is generally advantageous to perform heat recovery by a boiler, and the downstream of the reburning furnace 11 A boiler is connected to and the cooling of the combustion gas by water injection is adjusted so that the temperature after combustion of the pyrolysis gas in the re-combustion furnace 11 is around 1000 ° C.

(1) Example-1 FIG. 1 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to Example-1 of the present invention. As shown in the figure, the re-combustion furnace 11 has a substantially cylindrical shape and is provided with a refractory furnace wall 11b inside, and the top part 11a is directed to the inlet (gas inlet) 13 of the pyrolysis gas at the center of the upper end. A circular conical plate 14 is integrally formed around the gas introduction port 13 so as to be formed in a truncated cone shape whose diameter is gradually reduced upward. A plurality of air blowing nozzles (air blowing ports) 15a are formed in the seat plate 14 at intervals in the circumferential direction so as to be inclined so as to generate a swirling flow. Further, a cylindrical combustion air header 15 is mounted on the seat plate 14 so as to surround the nozzle 15a, and the air introduction pipe 15b is connected to the air header 15. Further, in the air header 15, a ring-shaped cooling water header 16 having a plurality of cooling water spray nozzles 16a in the circumferential direction facing each nozzle 15a is provided, and the cooling water header 16 has a cooling water introducing pipe 16b. Are connected. The air header 15
An outward flange 15c is integrally formed around the lower end of the furnace, and is connected to an outward flange 11c integrally formed around the top end of the furnace 11 by a connector 15d. As described above, the re-combustion burner (re-combustion region) 12 is formed on the top of the furnace 11.

Description of operation Pyrolysis gas G generated by heating waste
From the exhaust duct 9 to the reburning burner 12. Pyrolysis gas G from the inlet 13 at the center of the reburning burner 12
Are blown into the furnace 11. An air header 15 is provided so as to surround the central portion for blowing pyrolysis gas, and a plurality of air blowing nozzles 15 a of the air header 15 are provided.
Air B is blown into the furnace 11 from the inside. This nozzle 15
Since the central axis of a is slightly deviated from the blowing direction of the pyrolysis gas G, the flow of the air B blown into the furnace 11 becomes a swirl flow, which is well mixed with the pyrolysis gas G and burns. As described above, the cooling water W blown into the air from the cooling water spray nozzle 16a in the air header 15 is the air B.
At the same time, it is mixed well with the pyrolysis gas G, and evaporates when the pyrolysis gas G burns to uniformly cool the combustion gas.

Although not shown, the pilot burner, the flame detector, the cooling water flow rate control device and the air flow rate control device for initial ignition and for safety (always lit so that the flame of the reburn burner does not go out) are provided. Top 11 inside the furnace 11
It is provided in a.

The control of the reburning burner 12 of this embodiment is carried out by controlling the amount of cooling water W blown in. That is, since the amount and composition of the pyrolysis gas G reaching the re-combustion furnace 11 fluctuate, only the amount of blown water is controlled so that the furnace temperature becomes constant at 900 ° C. in order to cope with the fluctuation. On the other hand, the amount of blown air is not included in this adjustment loop, and a constant flow rate (the flow rate is usually increased a little) is secured, and the flow rate is occasionally reviewed and adjusted as necessary.

In the reburning furnace 11 of this embodiment, the heat generation amount of the pyrolysis gas G is not relatively large (LHV = 1500k).
(Cal / Nm ³ or less) This is intended for a furnace in which a pyrolysis gas G is introduced, and therefore, it can be dealt with only by blowing cooling water into the reburning burner 12.

(1a) Example-1a FIG. 2 is an enlarged sectional view showing a reburning burner portion which is a part of the reburning furnace according to Example-1a of the present invention. As shown in the figure, in the re-combustion furnace 11-1a of this example, following the re-combustion area 12 provided at the top of the re-combustion furnace 11 described above, a second re-combustion area 12-1 is provided above it. It is provided. The re-combustion region 12a has an inlet 13 (not shown) for the produced pyrolysis gas G below, and the shape of the furnace 11 in the re-combustion region 12a is a frusto-conical shape in which the inner diameter is gradually increased upward. An air header 15 is provided around the re-combustion region 12-1 above the introduction port, and a plurality of air blowing nozzles 15a of the air header 15 are deflected so as to generate a swirl flow. Air B is blown into the furnace 11 from 15a to generate a swirling flow. Further, above the air header 15, a cooling water header 16 having a plurality of cooling water spray nozzles 16a provided at intervals in the circumferential direction is provided, and the cooling water W together with the air B is supplied to the furnace 1.
1 is sprayed toward the center.

Since the other structures are common, the common members are denoted by the same reference numerals and shown in FIG. 2, and the description thereof is omitted. In addition, the reburning furnace 11-1 of this example
Regarding the operation of a, the basic operation is common except that the pyrolysis gas flows upward or downward.

(1b) Example-1b FIGS. 3 (a) and 3 (b) are enlarged cross-sectional views showing a reburning burner portion which is a part of the reburning furnace according to Example-1b of the present invention. FIG. As shown in FIG. 3, in the reburning furnace 11-1b of this example, at least the furnace top is formed into a cylindrical body, and the introduction port 13 for the pyrolysis gas G is provided at one end thereof, as shown in FIG. In addition, the pyrolysis gas G is in the furnace 11-1b.
Is introduced in the tangential direction of the cylindrical cross section of to generate a swirling flow.
Air-blowing nozzles 15a are provided on both sides of the inlet 13, and cooling water jet slips 16a are also provided.

Since other structures are common, the common members are denoted by the same reference numerals and shown in FIG. 3, and the description thereof is omitted. In addition, the reburning furnace 11-1 of this example
Regarding the operation of b, since dust and the like do not adhere to the furnace wall unless the combustion temperature becomes high (1200 ° C or higher),
Combustion is promoted by swirling the pyrolysis gas. The other basic operations are the same as those in the above-mentioned embodiment, and the description thereof will be omitted.

(2) Example-2 FIG. 4 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to Example-2 of the present invention. As shown in the figure, in the re-combustion furnace 11-2 of the present example, a cooling water spray pipe 17 is provided at the center of the introduction port 13 for the pyrolysis gas G so that the nozzle 17a at the lower end thereof is directed into the furnace 11. This is different from the reburning furnace 11 described above. In addition to the cooling water, the cooling water spray pipe 17 supplies fuel to the reactor 1 during warming up.
A cooling water supply pipe 18 and a fuel supply pipe 19 are connected via a switching valve 20 so that the water can be sprayed into the inside of the fuel cell 1. Further, the outer peripheral surface of the cooling water spray pipe 17 is coated with refractory refractory or porcelain ceramics. Since other configurations are common, common members are denoted by the same reference numerals and shown in FIG. 4, and description thereof is omitted.

Operation and Description In the re-combustion furnace 11-2 of this example, the pyrolysis gas G is exchanged with the air B from the nozzle 17a of the cooling water injection pipe 17 in the recombustion burner 12 for injecting the pyrolysis gas G. The cooling water W is blown into the pyrolysis gas G immediately before being mixed and burned. Of course, as in the reburning furnace 11 of the above-described embodiment, the air B is discharged from the plurality of air blowing nozzles 15a of the air header 15.
Is blown into the furnace 11-2, and the blown air B is swirled, mixed well with the pyrolysis gas G, and burned. Further, the cooling water W blown into the air inside the header 15 from the cooling water spray nozzle 16a inside the air header 15 is mixed well with the thermal decomposition gas G together with the air A.
Evaporates when it burns, cooling the combustion gas uniformly.

By switching the switching valve 20 of the cooling water injection pipe 17, fuel such as oil is blown from the fuel supply pipe 19 during warm-up preheating of the re-combustion furnace at the time of startup to preheat (usually, the temperature in the furnace is 50%).
(Until the temperature rises to about 0 ° C.), and during steady operation, the switching valve 20 is switched again to blow the cooling water from the cooling water supply pipe 18. When the temperature of the pyrolysis gas G is high, the hydrogen chloride gas contained in the pyrolysis gas G is cooled by the cooling water spray pipe 17
However, in the case of this example, since it is coated with refractory refractory or porcelain ceramics, there is no such possibility.

The re-combustion furnace 11-2 of this example uses the pyrolysis gas G.
It is applicable when the temperature is high (500 ° C. or higher).
If the temperature of the pyrolysis gas G is 400 ° C. or lower, the pyrolysis gas G becomes too cold in the recombustion burner 12, and as a result, the tar component is condensed from the pyrolysis gas G, and the dust inside the recombustion burner 12 is condensed. This is because it may lead to adhesion and deposition on the inner wall of the burner and cause a burner malfunction.

(3) Example-3 FIG. 5 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to Example-3 of the present invention. As shown in the figure, the re-combustion furnace 11-3 of this example has a refractory furnace wall 1
A plurality of cooling water spray pipes 21 are circumferentially spaced at the upper end of the cylindrical portion 1b, and the injection nozzle 21a at the lower end is connected to the furnace 11-3.
It is provided so as to be inclined obliquely downward toward the central axis line. The cooling water sprayed from these spray nozzles 21a is sprayed toward the tip (lower end) direction of 1/2 of the length (distance between the up and down directions: 1.5 m in this example) of the reburning flame F. The length and inclination angle of the cooling water spray pipe 21 are set. Since other configurations are common, common members are denoted by the same reference numerals and shown in FIG. 5, and description thereof is omitted.

Operation and Explanation In the reburning furnace 11-3 of this example, the reburning furnace 1 of Example-1 is used.
In addition to the cooling water injection in 1, the lower part 1 of the reburn flame F
Water is sprayed from / 2 toward the tip. In the case of the re-combustion furnace 11, there is a problem that the flame F may become unstable and disappear if the temperature of the combustion gas is lowered to 900 ° C. by blowing water into the re-combustion burner 12 depending on the gas composition. This is the solution.

In the re-combustion furnace 11-3 of this example, the adiabatic theoretical combustion flame temperature is controlled to 1400 to 1600 ° C. by spraying water from the water injection nozzle 16a in the re-combustion burner 12 part, and then cooled. Nozzle 2 of water spray pipe 21
The temperature is lowered to 900 ° C. by cooling water blown into the flame F from 1a. Actually, immediately after the outlet of the burner 12, not all of the pyrolysis gas G burns instantaneously, but all of the flame F part burns uniformly. Therefore, the blowing point of the water blown into the flame F may leave an unburned portion unless it is blown in the tip direction from at least ½ of the flame length (usually about 1.5 m). Further, the temperature of the combustion gas cooled by spraying with water should ideally be uniform, but in reality, it becomes nonuniform. However, even if it becomes non-uniform, unburned gas CO remains partially unless it is at least 500 ° C. or higher. For that purpose, it is desirable not only to pay attention to the blowing point as described above, but also to blow with fine water droplets from as many points as possible.

(4) Example-4 FIG. 6 is an enlarged sectional view showing a reburning burner portion which is a part of the reburning furnace according to Example-4 of the present invention. As shown in the figure, the re-combustion furnace 11-4 of the present example uses the pyrolysis gas G
The re-combustion furnace 11 is different from the above-described re-combustion furnace 11 in that an air blowing tube 22 is provided in the center of the introduction port 13 of the above so that the blowing port 22a at the lower end thereof is directed into the furnace 11-4. The outer wall surface of the metal air blowing tube 22 is covered with castable refractory or porcelain ceramics. Although illustration is omitted, by mounting a swirl vane on the blowing port 22a at the lower end of the air blowing pipe 22, the blown air can be swirled to improve mixing with the pyrolysis gas G. Since the other configurations are common, the same reference numerals are used for the common members in FIG.
, And the description is omitted.

Operation and Explanation There are cases where the temperature of the combustion gas cannot be appropriately lowered only by injecting the cooling water, and in that case, it is necessary to blow a little more air. However, when a large amount of air is blown in, the mixture of the pyrolysis gas G and the air A deteriorates, and good combustion cannot be obtained (blown out). This example solves this problem. Compared to the reburning furnace 11 of the example-1, the reburning furnace 11-4 of the present example has an air blowing pipe 22 in the center of the reburning burner 12. Since it is provided, the pyrolysis gas G is satisfactorily mixed by the air blown from the blow-in port 22a at the lower end and the air inside and outside the air blow-in nozzle 15a in the periphery thereof. Further, similarly to the reburning furnace 11-3 of Example-3, water is sprayed from the nozzle 21a of the cooling water spray pipe 21 to the flame F after combustion.

(5) Example-5 FIG. 7 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to Example-5 of the present invention. As shown in the figure, in the re-combustion furnace 11-5 of this example, a temperature rising burner tube 23 also serving as an air blowing tube is provided at the center of the introduction port 13 for the pyrolysis gas G, and a blowing port 23a at the lower end of the furnace is provided. It is different from the above reburning furnace 11 in that it is provided inside 11. Further, the fuel supply pipe 24 is connected to the temperature rising burner pipe 23 via a control valve 24a, and the air supply pipe 25 is connected to the temperature raising burner pipe 23 via a control valve 25a. Therefore, at the time of start-up, not only the fuel can be blown from the blowing port 23a as the temperature raising burner 23, but also the air can be blown after the temperature is sufficiently raised. Further, the outer peripheral surface of the temperature rising burner tube 23 is covered with castable refractory or porcelain ceramics. Since other configurations are common, common members are denoted by the same reference numerals and shown in FIG. 7, and description thereof is omitted.

Operation and Description In order to start the reburning furnace 11-5 from a room temperature state, first, auxiliary fuel such as heavy oil or LPG is heated by the burner tube 2
It must be blown from No. 3 into the furnace 11-5, burned, and gradually raised in temperature. That is, the temperature in the furnace is about 500 ° C.
After that, the pyrolysis gas G can be reburned. To raise the temperature, a temperature raising burner 23 is usually provided separately from the reburning burner 12 (the temperature raising burner is not shown in Examples 1 to 4), but in the present example, the temperature raising burner is used. 23
And the reburning burner 12 are combined. That is, when the temperature is raised, the control valve 25a of the air supply pipe 25 is closed and the control valve 24a of the other fuel supply pipe 24 is opened. Then, after the temperature is sufficiently raised, the control valve 24a of the fuel supply pipe 24 is closed and the control valve 25a of the air supply pipe 25 is opened in a state where the pyrolysis gas G is re-combusted, and air is introduced into the furnace 1-5. It is blown in, mixed with the pyrolysis gas G, and reburned. In the reburning state, the same operation as the above-described reburning furnace 11-3 of the third embodiment is performed.

[0065]

As is apparent from the above description,
The pyrolysis gas re-combustion furnace according to the present invention has the following excellent effects.

1. Dust does not adhere or grow on the inner wall of the reburn furnace.

2. The residence time of gas at 850 ° C or higher is always 2 in the reburning furnace even if the composition of waste and the amount of waste are changed.
You can secure more than a second. As a result, the dioxin is decomposed and the solid combustibles (for example, char) contained in the pyrolysis gas are completely burned out (the combustibles are hardly contained in the finally separated dust).

3. The amount of CO and NOx contained in the reburning furnace outlet gas is very small.

4. Overall equipment cost is low, including other equipment such as dust collectors and draft fans on the downstream side.

5. The above effects 1 to 4 can be achieved even if the quality of waste and the amount of waste processed vary.

6. Since the sprayed water is extremely uniformly mixed in the combustion gas, the temperature of the combustion gas is lowered and not only the generation of NOx and the melting and adhesion of dust can be prevented, but also
It has advantages such as reduction of the amount of dioxins in exhaust gas and prevention of increase of exhaust gas amount.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a reburning burner portion that is a part of a reburning furnace according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a reburning burner portion, which is a part of the reburning furnace according to the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a reburning burner portion that is a part of the reburning furnace according to the first embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view showing a reburning burner portion which is a part of a reburning furnace according to a second embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to a third embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing a reburning burner portion which is a part of a reburning furnace according to Embodiment 4 of the present invention.

FIG. 7 is an enlarged sectional view showing a reburning burner portion which is a part of a reburning furnace according to embodiment-5 of the present invention.

FIG. 8 is a schematic diagram showing an example of an exhaust gas treatment facility including a waste gasification and melting furnace and a reburning furnace.

FIG. 9 is a cross-sectional view showing an outline of a simple refractory-lined inner wall structure type reburning furnace according to the related art-A.

FIG. 10 is a cross-sectional view showing an outline of a water-injection type refractory-clad inner wall structure type reburning furnace according to the related art-B.

FIG. 11 is a cross-sectional view showing the outline of a circulating exhaust gas blowing type reburning furnace according to related art-C.

FIG. 12 is a cross-sectional view showing an outline of a swirl melting furnace according to related art-D.

[Explanation of symbols]

1 11 / 11-1a / 11-1b / 11-2 / 11-3 / 11-4 /
11-5 Reburning Furnace 11a Top 11b Refractory Furnace Wall 12 Reburning Burner (Reburning Area) 13 Pyrolysis Gas Inlet (Gas Inlet) 14 Seat Plate 15 Combustion Air Header 15a Air Injecting Nozzle (Air Inlet) 16 ring-shaped cooling water header (water spray device) 16a cooling water spray nozzle 17 cooling water spray pipe 17a nozzle 18 cooling water supply pipe 19 fuel supply pipe 20 switching valve 21 cooling water spray pipe 21a injection nozzle 22 air blowing pipe 22a blowing port 23 Air-Blowing Pipe Double-Temperature Burner Pipe 23a Blow-in Port 24 Fuel Supply Pipe 24a / 25a Control Valve 25 Air Supply Pipe

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3K061 AA16 AB02 AC06 AC07 BA02                       FA02 FA12 FA21 FA23                 3K062 AA16 AB02 AC01 AC06 AC07                       BA02 BB02 CB03 DA01 DB28                 3K065 AA16 AB02 AC01 AC06 AC07                       BA02 FA15 FA21 FB03 FB07                 3K078 AA02 BA02 BA22 BA24 BA26                       CA02 CA18

Claims (11)

[Claims] 1. The above flammability is obtained by partial combustion of combustible waste such as general waste, industrial waste, waste oil and liquid waste, or indirect heating, or indirect heating and partial combustion. Generated by thermal decomposition of waste
A recombustion furnace for waste pyrolysis gas for complete combustion of combustible pyrolysis gas containing hydrocarbon, organic matter, oil vapor, and corrosive gas such as dust and hydrogen chloride together with the dust, An inlet for pyrolysis gas is provided at the end of the furnace, and a plurality of combustion air blowing ports are provided in the circumferential direction to form a reburning region, and each air blowing port is provided in the reburning region. A re-combustion furnace for waste pyrolysis gas, comprising a water spraying device for spraying cooling water into the furnace together with the air. 2. A cylinder that surrounds each air blowing port while tilting or twisting each air blowing port so that a swirl flow is generated around the gas flow introduced from the pyrolysis gas introducing port. 2. The waste product according to claim 1, further comprising a cooling water header provided with a plurality of cooling water spray nozzles in the circumferential direction, the cooling water header facing the respective air blowing ports in the air header. Recombustion furnace for pyrolysis gas. 3. A central axis portion of the introduction port of the pyrolysis gas,
The recombustion furnace for waste pyrolysis gas according to claim 1 or 2, wherein the cooling water spray pipe is provided with a nozzle at the lower end thereof directed toward the center of the furnace. 4. A plurality of cooling water spray pipes are circumferentially spaced above the re-combustion furnace, and the injection nozzle at the tip has a flame length (distance between upstream and downstream directions) generated during re-combustion. The disposal according to any one of claims 1 to 3, wherein the cooling water is blown in a direction closer to the front end than 1/2 so as to be inclined toward the central axis of the furnace toward the downstream side. Recombustion furnace for pyrolysis gas. 5. The shape of the furnace in the downstream direction of the re-combustion region at the top of the re-combustion furnace is a frusto-conical shape in which the diameter gradually decreases toward the upstream, or a frusto-conical shape in which the diameter gradually decreases toward the upper end of the cylindrical shape. The recombustion furnace for waste pyrolysis gas according to any one of claims 1 to 4, characterized in that the furnace has a changed shape. 6. An air blowing pipe is provided at the center of the introduction port of the pyrolysis gas at the top of the re-combustion furnace with the blowing port at the lower end thereof facing the inside of the furnace.
A recombustion furnace for waste pyrolysis gas according to any one of 5 above. 7. The recombustion furnace for waste pyrolysis gas according to claim 3, wherein a cooling water supply pipe and a fuel supply pipe are connected to the cooling water spray pipe via a switching valve. 8. The cooling water spray pipe or the air blowing pipe is made of a metal pipe, and the outer wall surface thereof is coated with a refractory refractory material, castable refractory material, or porcelain ceramics. 4, 7 or 8
Re-combustion furnace for waste pyrolysis gas described. 9. The sewage or the like generated in a dust pit or separated from dust by being compressed in a dust dispenser is used as a part of the cooling water. Re-combustion furnace for waste pyrolysis gas described. 10. The adiabatic theoretical combustion flame temperature in the re-combustion furnace is controlled to be 1400 to 1600 ° C., and then cooling water is sprayed to the flame to bring it to near 900 ° C. (850 ° C.).
The temperature of the combustion gas is controlled so as to be at least 500 ° C. or higher even locally, but the temperature of the combustion gas is controlled to be at least 500 ° C. or higher. Control method. 11. The control of the re-combustion region is performed so that the temperature in the furnace is kept constant by controlling only the amount of blown water for cooling while keeping the amount of blown air constant. 11. The method for controlling a recombustion furnace for waste pyrolysis gas according to any one of 1 to 10.